Drier for aggregates and the like



July 21, 1942*. VERMAN 2,290,765

.DRIER FOR AGGREGATES AND THE LIKE Filed April 30. 1941 2 Sheets-Sheet l PIE'. l l5 5l 53 fr I BY 3 y/777 July 21, 1942. l. J. OVERMAN 2,290,765

DRIER FOR AGGREGATES AND THE LIKE Filed April so, 1941 2 Sheets-sheet 2 ZI /5 Z4 /5 jl l5 Patented July 21, 1942 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a drier for aggregates and the like which is particularly adapted for preparing aggregates for asphalt and other types of paving but is useful for other purposes as well.

One object of the invention is to provide a drier which is of suflcient capacity to be eciently used on a paving contract but yet is of compact construction easily transported on a truck or trailer.

Another object of the invention is to improve the overall efficiency of a portable drier of the type described and to increase the speed with which a given quantity of aggregate or other material may be dried. To this end there is provided a drier having inner and outer rotatable drums through which the material to be dried may be successively passed. Said material is introduced into one end of the inner drum which is preferably of a tapered form and receives the material at the smaller end. The material leaves the inner drum at the larger end and its direction of movement is reversed so that it returns through the space between the inner and outer drums and is discharged at the same end of the apparatus at which it entered. In its double passage through the apparatus the material is heated and the heated air and entrained moisture are drawn off by an exhaust fan.

One feature of the invention resides in the particular arrangement of heating units by which the maximum drying effect is obtained.

Another feature of the invention resides in a particular arrangement of parts for removal of the air and moisture.

Other objects and features of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. 1 is a side View of a drier constructed in accordance with the invention, a protective outer casing ordinarily employed therewith having been removed to show other parts in detail. Fig. 2 is an end view of the same with the protective casing in place. Fig. 3 is a central sectional View in elevation taken substantially on the line 3-3 of Fig. 2.

In the preferred form of the apparatus shown by Way of illustration in the drawings, there are provided base members I which may be mounted in a truck or trailer or which may be a part of the bed of a truck or trailer. A pair of shafts I I are mounted on bearings I2 on the base members I0 and one or both of said shafts may be driven by suitable power means connected thereto as by a pair of rollers I4 and said rollers are engaged by a pair of metal rings I5 Which are secured to the outer surface of a rotatable drum I6. The

Vrollers I4 are so placed that they support the weight of the drum and frictionally rotate the same when the shafts II are rotated. One or more of the rollers I4 may be provided with flanges I'I engaging the edges of the corresponding ring I5 to prevent undesired longitudinal movement. At the opposite ends of the drum I6 there are provided stationary closure members I8 and I9 which are suitably supported in any desirable manner.

Within the drum I6 there is mounted a conical inner drum 20 which is secured to the outer drum I6 by spacer bolts 2| or other suitable fastening means. An intake chute 22 is suitably supported at one end of the apparatus and is adapted to receive the material to be dried and to discharge the same through a suitable central opening in the closure I8 into the small end of the inner drum 2li. Said inner drum is provided on its inner surface with upstanding plates 23 which are adapted to lift the aggregate from the lower part of said drum and to advance the same toward the left in Fig. 3. The plates 23 thus provide a mixing and aerating action which assi-sts in the drying.

As will be seen from Fig. 3, the inner drum 20 terminates short of the closure member I9 so that the aggregate may pass from the large end of the inner drum to the space between said drums. The inner surface of the outer drum I6 is provided with a plurality of inwardly extending plates 24 which are pitched in the opposite direction to the plates 23 and thus serve to move the partially dried aggregate to the right in Fig. 3. The closure member I8 terminates short of the lower edge of the drum I6 as shown at 25 in Fig. 2. Thus, the material may be discharged from said drum into any suitable receiver.

Adjacent the lower edge of the closure member I8 there is mounted a cylindrical shell 26 forming an air inlet opening in which there is positioned a fuel burner 2l. Said burner may be of any well known type adapted to burn a liquid or gaseous fuel and may be supported in any desirable manner. As best seen in Fig. 3, the burner 21 is positioned to direct its ame 28 into the largest portion of the space between the inner and outer drums and to place said flame directly on the outer surface of the inner drum 20.

At the opposite end of the apparatus a similar burner 29 is directed through a similar air inlet a coupling I3. On each of the shafts II there is opening formed by a cylindrical member 3i), said member 30 being mounted on the closure I9. The burner 29 is positioned to direct, its iame directly into the large end of the inner drum 20.

At any suitable point,-as for example, on the top of a protective outer casing 3|, there is mounted an exhaustl fan 32 to the inlet of which there is connected an air conduit 33. Said air conduit is provided with two branches, one branch 34 connected with the inlet chute 32 and the other branch 35 leading through a suitable opening in the closure member I8 and communicating with the space between the inner and outer drums. A butterfly valve or damper 36 is mounted in the branch 35 and may be set at any desired angle to proportion the amount of air drawn through the two branches. A check gate 31 is pivotally mounted within the inlet chute 22 at a point beyond the air conduit 34 and normally hangs directly downwardly except when material is being introduced through said chute. The weight of said gate is suiicient to prevent appreciable movement thereof due to the pressure difference maintained by the exhaust fan but is not sufficient to prevent the entrance of said material. Said gate thus permits entrance of material to be dried but minimizes entrance of air into the intake chute.

By means of the construction just described, all parts of the path of travel of the material are thoroughly heated and are thoroughly ventilated. The two burners 21 and 29 serve to heat the air and aggregate in the two portions of the material path inside and outside of the inner drum. The burner 21 in addition plays upon the inclined outer surface of the inner drum and thus supplies additional heat to the irst part of the material travel where the amount of moisture to be removed is the maximum. The moisture laden air is drawn from both parts of the material travel. The air from the interior of the inner drum I6 is taken through the inlet chute and the branch 34 of the air conduit while moisture laden air from the space outside the inner drum is taken through the branch 35. Since the air on the inside of the inner drum carries a greater percentage of moisture, it is important that it be removed more rapidly than that from outside the inner drum. A proper balance between the two streams of air may be maintained by adjusting the damper 36 and the total quantity of air withdrawn may be controlled by controlling the speed of the exhaust fan.

From the foregoing description it will be seen that the invention provides a very compact and eiiicient drier in which a large quantity of moisture may be removed from paving materials in a relatively small space.

The invention has been described in one of its preferred forms, the details of which may be varied by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

The invention claimed is:

1. In a drier for aggregates and the like, rotatable inner and outer drums through which material to be dried may be successively passed, a stationary closure for one end of said outer drum, said closure having an inlet opening, an inlet chute arranged to deliver said material through said inlet opening to the interior of said inner drum, means for heating the material in said drums, an exhaust fan, and an air conduit leading to said exhaust ian and having branches leading respectively from said inlet chute and from an opening in said stationary closure between said inner and outer drums, whereby air and entrained moisture may be drawn from the interior of said inner drum through said inlet chute and from the space between said drums through said last mentioned opening.

2. In a drier for aggregates and the like, rotatable inner and outer drums through which material to be dried may be successively passed, a stationary closure for one end of said outer drum, said closure having an inlet opening, an inlet chute arranged to deliver said material through said inlet opening to the interior of said inner drum, means for heating the material in said drums, an exhaust fan, an air conduit leading to said exhaust fan and having branches leading respectively from said inlet chute and from an opening in said stationary closure between said inner and outer drums, whereby air and entrained moisture may be drawn from the interior of said inner drum through said inlet chute and from the space between said dlums through said last mentioned opening, and a check gate in said inlet chute beyond said air conduit adapted to permit entrance of said material thereto and to minimize entrance of air to said chute from the outside atmosphere.

3. In a drier for aggregates and the like, rotatable inner and outer drums through which material to be dried may be successively passed, a stationary closure for one end of said outer drum, said closure having an inlet opening, an inlet chute arranged to deliver said material through said inlet opening to the interior of said inner drum, means for heating the material in said drums, an exhaustI fan, an air conduit leading to said exhaust fan and having branches leading respectively from said inlet chute and from an opening in said stationary closure between said inner and outer drums, whereby air and entrained moisture may be drawn from the interior of said inner drum through said inlet chute and from the space between said drums through said last mentioned opening, and a gate controlling air iiow in at least one of said branches to proportion the air drawn through said branches.

IVAN J. OVERMAN. 

